Drawings J.G. de Man

Johannes Govertus de Man (1850–1930) was a Dutch biologist and he was (assistant) curator at the “Rijksmuseum van Natuurlijke Historie” in Leiden (1872-1883), where he specialised in free-living nematodes and decapod crustaceans. After leaving the museum he continued this work as an independent researcher, mainly working from his house in Yerseke (Zeeland). Although he described nematodes from all continents, he paid ample attention to the nematodes from his near surroundings.

Copyrights and credits

The drawings by J.G. de Man can be downloaded for free. The copyrights of the drawings belong to the Laboratory of Nematology. Please contact the Laboratory (Lisette Groeneveld-Vervloed) for information on how to attribute the drawings when you want to use them in a publication or on a website.

J.G. de Man, 1896 (photographer: C. Henning, Middelburg)

In the course of time the Laboratory of Nematology has collected a number of drawings of De Man. A considerable number was made available on the website of the Laboratory of Nematology and in Wageningen UR Image Collection. The original drawings are kept at the Plant Protection Service in Wageningen and are on request available for further research.

De Man wrote several articles on his research in which his drawings were printed. Most of the drawings in this collection were published in five articles in the French journal Mémoires de la Société Zoologique de France.

In 1888, J.G. de Man published an article about new and poorly known North Sea nematodes, based on material collected from the ‘Kanaal door Walcheren’ and the fortifications of Vlissingen.Sur quelques Nématodes libres de la Mer du Nord nouveaux ou peu connus. (Mém. Soc. Zool. France 1 (1888): 1-51, pl. 1-4.)Full text / original drawings.

One year later (1889), De Man was paying attention to the nematodes of the southern part of the North Sea. De Man described twelve species from the previous island Walcheren, the fortifications of Vlissingen, the “Kanaal door Walcheren” (opened in 1873) and the mouth of the Schelde.Troisième note sur les Nématodes libres de la Mer du Nord et de la Manche (Mém. Soc. Zool. France 2 (1889): 182-216, pl. 5-8)Full text / original drawings.

In 1890, De Man published a follow-up paper about nematodes of the North Sea and Channel in 1890. In that article he gave additional descriptions of five species, previously described by Bastian from the South English Coast: Comesoma vulgare (a common species of the North Sea and Mediterranean); Spira parasitifera (nowadays known as Spirinia parasitifera, a cosmopolite); Chromadora filiformis (nowadays Chromadorella filiformis, cosmopolite); Cyatholamus punctatus (nowadays Praeacanthonchus punctatus, a North Sea species); Oncholaimus glaber (now known as Viscosia glabra) and Oncholaimus viscosus (nowadays Viscosia viscosa, a common North Sea species).Quatrième note sur les Nématodes libres de la Mer du Nord et de la Manche. Mém. Soc. Zool. France 3 (1890): 169-194, pl. 3-5Full text / original drawings.

In a “fifth note” (1893), De Man described several species from the North Sea and Channel. Some of these descriptions reconsider nematodes that had been described before by Bastian in 1865 and Eberth in 1863. A number of species were new.Cinquième note sur les Nématodes libres de la Mer du Nord et de la Manche (Mém. Soc. Zool. France 6 (1893): 81-125, pl. 5-7)Full text / original drawings.

In 1907, De Man published an article with descriptions and drawings of nematodes which he had observed in previous years along the coast of Zeeland, mainly along the shore of the Oosterschelde near Veere and Yerseke and one species (E. terricola) from brackish soil on the island of Walcheren. Sur quelques espèces nouvelles ou peu connues de Nématodes libres habitant les côtes de la Zélande (Mém. Soc. Zool. France 20 (1907): 33-90, pl. 1-4.)Full text / original drawings.

Original drawings and copies on transparent paperThe original drawings of de Man have probably been composed with a silver needle and sepia ink on board. On many drawings we find some remarks added by De Man that were not included in the printed version. De Man’s work was usually printed abroad. In the period that De Man composed his drawings, at the end of the 19th century there were no possibilities to make a photocopy before sending the drawings to the printer. In a letter from De Man’s sister to Schuurmans Stekhoven in 1932, she noted that her brother was very afraid for loss of the package. As a precaution measure he made copies on transparent paper; these were not meant to be published, therefore he did not add names. In the collection there are many of these copies; they turned brown but still give a nice impression on his way of working.

Unpublished or unfinished drawingsIn the collection there are a number of drawings that differ from the other drawings; drawings in an early phase, drawings that had been replaced by more accurate ones, and drawings that (presumably) have never been published. In most cases, the name of the nematode is lacking, in other cases a provisional name has been added with a pencil. These drawings are shown to give you an impression of De Man’s way of working.

Notes of J.G. De ManDe Man studied his nematodes preferably alive; by doing so he made notes regarding the movement and morphology based on several specimens. A part of his original notes are still present. The names, as presented here, are the names as used by De Man. De Man also left us an exercise-book with his observations regarding terrestrial, brackish water and freshwater nematodes. The cover of the exercise-book bears the title “Nématodes, libres, marins, de la région de Cette”. The handwriting on the cover is not from De Man.